We have already seen a similar example where the subordinate conjunction that was removed from the text:
Such constructions involving a clause embedded within a clause may be awkward, but they are not ungrammatical. For a complete list of verbs that have occasionally lost the subordinate conjunction that from the head of the following complement, see that in volume 3.
Summary: In accord with the earliest textual sources, restore the subordinate conjunction that in 1 Nephi 13:32 (“which thou beholdest that they are in”).